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Biomedical subjects

K MacCannell

Publications and source records attributed to K MacCannell.

9 recordsLinked to original sources

Gastrointestinal inflammation: focus on the vascular endothelium.

Ischemia of the intestine predominantly affects the small bowel and colon, and may ensue from a variety of causes, ranging from radiation enteritis to the use of drugs that affect the intestinal vasculature. Gut ischemia has historically been thought of as "large-vessel" disease, but microcirculatory pathology and ischemia-reperfusion injury is increasingly being implicated in gut infections and even in chronic idiopathic inflammatory processes involving the gut, such as ulcerative colitis and Crohn's disease.

Endothelium, Vascular↗

Midazolam in upper gastrointestinal endoscopy: a single-blind dose-finding study.

Midazolam is a water soluble benzodiazepine with potent sedative and amnestic properties. Sixty unpremedicated patients who were to undergo upper endoscopy for diagnostic purposes were enrolled in an open, non-randomized study to assess the efficacy of 4 increasing dosages of midazolam (0.05, 0.10, 0.15 and 0.20 mg/kg). Efficacy measures included Trieger test (psychomotor drawing), presence of anterograde amnesia, patient rating (PR) of the sedation, evidence of inflammation at the site of the injection and physician's global assessment (PGA). The 4 patient groups were similar in age, sex and ASA class. Eight of the 15 patients who received the 0.05 mg/kg and 1 patient each in the 0.10 mg/kg and 0.15 mg/kg group were considered to be treatment failures and required supplemental diazepam. PR (excellent-good) was constant for all doses throughout. Nearly all patients had anterograde amnesia. Deterioration in the Trieger test results was associated with increasing dose (ANOVA, p less than 0.05). There were no significant changes in vital signs. Signs of phlebitis were noted in two patients who received both diazepam and midazolam. PGA rating rose from 26.7% (0.05 mg/kg) to 80.0% (0.20 mg/kg) (p less than 0.01). Few adverse effects (unrelated to dosage) were noted. Midazolam is a well tolerated benzodiazepine which provides satisfactory sedation for endoscopy. If no premedication is given, there are no benefits to be gained from using a dose greater than 0.10 mg/kg.

Adult↗

Use of a specific mesenteric vasodilator peptide, urotensin I, to reduce afterload in the dog.

The authors have previously demonstrated that urotensin I, a peptide derived from the urophysis of bony fish, reduced arterial blood pressure of anesthetized dogs by selective dilation of the mesenteric vascular bed. In the present experiments, intravenous infusions of urotensin I produced a sustained increase in cardiac output and decrease in peripheral resistance. The magnitude of the hypotensive response and of reflex effects on the heart appeared to be limited quantitatively by the unique mechanism of action. Coronary artery flow was maintained in spite of a decrease in coronary filling pressure, presumably as a consequence of coronary autoregulation and the increased cardiac output. No direct cardiac effects were observed on close-arterial injection into a coronary artery. An agent with these characteristics which will decrease left ventricle afterload is of interest in the management of myocardial failure and possibly of cardiogenic shock. In dogs in which minimal myocardial injury was produced by injection of thrombin into a coronary artery, intravenous infusions of urotensin I restored minimal but statistically significant elevations in right and left ventricular end-diastolic pressures to preinsult levels.

Animals↗

Dilatation of the mesenteric vascular bed of the dog produced by a peptide, urotensin I.

Urotensin I, a peptide derived from the urophysis of bony fish, produced hypotension when administered intravenously in small doses to pentobarbital-anesthetized dogs. The mechanism of this hypotensive response was mainly, if not exclusively, due to dilatation of the cephalic and caudal mesenteric arteries. Neither the hypotensive response nor the mesenteric vasodilator response was prevented by adrenergic, histaminergic or muscarinic receptor blockade. In the doses employed, urotensin I constantly caused minimal increases in heart rate and left ventricular dp/dt; these changes could be prevented by prior administration of propranolol, indicating that they were probably reflex in origin. The authors suggest that the unique mechanism of action of the peptide may make it a valuable tool in studies of the mesenteric circulation, particularly in experimental shock; moreover, the peptide may prove useful in situations in which afterload reduction in the absence of cardiac stimulation is desired.

Animals↗

Marijuana-produced changes in pain tolerance. Experienced and non-experienced subjects.

The effect of marijuana and placebo on pain tolerance was compared in cannabis-experienced and naive subjects. A statistically significant increase in tolerance was observed after smoking marijuana. Although there was no statistically significant interaction between the drug effect and having had previous cannabis experience, there was a definite trend towards a greater increase for the experienced (16%) compared to the naive group(8%).

Adult↗